Such cylinder head gaskets with beaded outer plate layers and a one-piece, metallic ring acting as a so-called stopper ring which encloses the combustion chamber hole and projects over both main surfaces of the inner plate layer are to be taken from FIG. 2 of DE-A-195 36 718 and from FIG. 8 of DE-A-42 19 709. In the manufacture of these known cylinder head gaskets, a circular opening whose diameter exceeds the diameter of the combustion chamber hole by at least twice the width of the stopper ring is punched out of the inner plate layer. There is also punched out of a metal sheet whose thickness exceeds the thickness of the metal sheet of the inner plate layer by the sum of the projections of the stopper ring over the inner plate layer, a stopper ring which is inserted into the opening of the inner plate layer and is optionally soldered thereto (see DE-A-195 36 718). In the manufacture of these known cylinder head gaskets quite a lot of waste is produced in the form of the circular disc punched out of the inner plate layer and the circular disc resulting from punching out the stopper ring. A further disadvantage of these known cylinder head gaskets is to be seen in that the stopper ring has to be calibrated with respect to its height as the thickness tolerances of thicker metal sheets are correspondingly larger than the thickness tolerances of thinner metal sheets.
To eliminate these disadvantages, cylinder head gaskets with beaded outer plate layers have already been constructed wherein the inner plate layer has an offset bend around the combustion chamber hole so that a ring-shaped area of the inner plate layer enclosing the combustion chamber hole projects on the one side and is set back on the other side with respect to the inner plate layer. Placed on the last-mentioned side of this ring-shaped area is a sheet metal ring which is congruent with this area and the sheet thickness of which is twice as large as the projection of the offset bent area of the inner plate layer on the other side, which results in a ring-shaped,stopper structure for the beads of the two outer plate layers. However, these known cylinder head gaskets have another disadvantage: Tensions are caused by the offset bending in the inner plate layer around the combustion chamber hole, which result in the offset bent inner plate layer arching and warping in the vicinity of the combustion chamber hole. This causes problems for the gasket manufacturer when handling and joining the layers of the gasket plate and also problems when assembling the engine. Moreover, this distortion of the inner plate layer makes it difficult to adhere to the layer tolerances of the components of the cylinder head gasket around the combustion chamber hole, i.e., in the most critical area of a cylinder head gasket.
In cylinder head gaskets of the kind described above with beaded outer plate layers, the stopper ring or the ring-shaped stopper structure consisting of the offset bent area of the inner plate layer and the sheet metal ring not only has the task of preventing undesirably strong deformations of the beads of the outer plate layers on tightening the cylinder head screws and while the engine is running, but also owing to the stopper ring or stopper structure described above, the aim is achieved that the highest specific surface pressures between cylinder head and cylinder head gasket, on the one hand, and engine block and cylinder head gasket, on the other hand, occur immediately around the combustion chamber hole when the cylinder head gasket is installed.
Cylinder head gaskets of the kind first mentioned at the outset are also already known wherein the outer plate layers have no beads around the combustion chamber hole, and, nevertheless, a stopper ring-like structure is present around the combustion chamber hole in order to achieve the aim that the highest specific surface pressures between cylinder head gasket, cylinder head and engine block occur immediately around the combustion chamber hole, so the combustion chamber is sealed off also without beads on the outer plate layers. Naturally, the same problems and disadvantages arise with these known cylinder head gaskets as explained above for known cylinder head gaskets with beaded outer plate layers.